xfs: pass the exact range to initialize to xfs_initialize_perag

Currently only the new agcount is passed to xfs_initialize_perag, which
requires lookups of existing AGs to skip them and complicates error
handling.  Also pass the previous agcount so that the range that
xfs_initialize_perag operates on is exactly defined.  That way the
extra lookups can be avoided, and error handling can clean up the
exact range from the old count to the last added perag structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

1 files changed, 6 insertions, 22 deletions

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 5f0494702e0b..464f682eab46 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -296,27 +296,16 @@ xfs_free_unused_perag_range(
 int
 xfs_initialize_perag(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		agcount,
+	xfs_agnumber_t		old_agcount,
+	xfs_agnumber_t		new_agcount,
 	xfs_rfsblock_t		dblocks,
 	xfs_agnumber_t		*maxagi)
 {
 	struct xfs_perag	*pag;
 	xfs_agnumber_t		index;
-	xfs_agnumber_t		first_initialised = NULLAGNUMBER;
 	int			error;
 
-	/*
-	 * Walk the current per-ag tree so we don't try to initialise AGs
-	 * that already exist (growfs case). Allocate and insert all the
-	 * AGs we don't find ready for initialisation.
-	 */
-	for (index = 0; index < agcount; index++) {
-		pag = xfs_perag_get(mp, index);
-		if (pag) {
-			xfs_perag_put(pag);
-			continue;
-		}
-
+	for (index = old_agcount; index < new_agcount; index++) {
 		pag = kzalloc(sizeof(*pag), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
 		if (!pag) {
 			error = -ENOMEM;
@@ -353,21 +342,17 @@ xfs_initialize_perag(
 		/* Active ref owned by mount indicates AG is online. */
 		atomic_set(&pag->pag_active_ref, 1);
 
-		/* first new pag is fully initialized */
-		if (first_initialised == NULLAGNUMBER)
-			first_initialised = index;
-
 		/*
 		 * Pre-calculated geometry
 		 */
-		pag->block_count = __xfs_ag_block_count(mp, index, agcount,
+		pag->block_count = __xfs_ag_block_count(mp, index, new_agcount,
 				dblocks);
 		pag->min_block = XFS_AGFL_BLOCK(mp);
 		__xfs_agino_range(mp, pag->block_count, &pag->agino_min,
 				&pag->agino_max);
 	}
 
-	index = xfs_set_inode_alloc(mp, agcount);
+	index = xfs_set_inode_alloc(mp, new_agcount);
 
 	if (maxagi)
 		*maxagi = index;
@@ -381,8 +366,7 @@ out_remove_pag:
 out_free_pag:
 	kfree(pag);
 out_unwind_new_pags:
-	/* unwind any prior newly initialized pags */
-	xfs_free_unused_perag_range(mp, first_initialised, agcount);
+	xfs_free_unused_perag_range(mp, old_agcount, index);
 	return error;
 }